SCTE 104/35 Codex

A break starts with a message telling the splicer to leave the network for an ad. out_of_network_indicator is 1 when exiting the network and 0 when returning, and the splice point comes from the splice_time in the section, delivered far enough ahead to meet the pre-roll. While the event is still outside the pre-roll window it can be cancelled with the splice_event_cancel_indicator flag; once inside pre-roll or after the break has begun, a cancel is ignored. An event can be updated in place without a prior cancel, and the latest message that still meets the pre-roll constraints supersedes earlier ones. When out_of_network is 1, include a break_duration: it is the preferred way to signal when the break should end.